Stray Kat and spun alternator rotor

[cnap504]

Recently acquired a non-running 1982 Katana in fair shape.  Removed the tank and carbs for cleaning, two stroke oiled the cylinders and installed a new battery.  After letting the cylinder oil set for a day I turned the motor over manually, so far so good.  Figured I try the starter and it free spun, no clatter and no crank rotation.  I remember back in the day that some of the 1000 Katanas would spin the alt. rotor on the end of the crank.  Pulled the cover and rotor off, it’s eaten up pretty bad.  I’m going to use lapping compound and get as much good contact area back as I can, then put Loctite retaining compound on the surfaces.  Any suggestions welcome.

[Swiss Toni]

Well, you can’t do any harm by lapping with fine grinding paste. Try it, you’ve got nothing to lose. If you want to keep the Kat crank & rods, metal spraying/welding the taper might be an option … expensive, but an option nevertheless!

[Dezza]

That looks like it could get expensive. At least you're not yet emotionally attached to the bike. If my crank looked like that I would need counselling .

[Fazz711]

Try taking the high spots off before lapping. 

Looks pretty bad though. 

Don't think metal spray will up to it but spiral welding will do it. 

Not a cheap job though. 

[TonyGee]

thats in a bad way   after the lapping maybe a blob or two welds ?  yeah i know its crude as fuck but if it gets you on the road for a while till you can find a good crank. 

[buff]

I ended up getting an efe taper fitted on my old engine when i had the crank rebuilt. But ultimately having spun the original tapper three or four times I went over   an outboard alternator kit, a lot less weight on the crank to spin.

Edited May 27, 2021 by buff

[cnap504]

Talked to a friend of mine who has been in the mc repair and wrecking yard business for many years, his recommendation was after lapping the taper heat the rotor on a hot plate until it’s as hot as it will get then install to shaft and torque to spec.  This will allow the expanded rotor to cool and contract tightly to the crank taper.  Also he suggests making sure the ign timing is standard not advanced and maintaining a good proper battery that holds its charge 

Edited May 27, 2021 by cnap504

[Blubber]

Carefull not to overheat the rotor as the magnets loose their glue or strenght 

[Swiss Toni]

Then you will have problems!

[cnap504]

Hello again,  can anyone give me the part number for the fuel adjustment screws on this ‘82 GS1000SZ ?   I looked on an online microfiche and they are not shown, presumably because they are “non-serviceable” plugged off pieces.  I have aluminum top cv carbs (US market), measured at 34mm.  Thanks 

[skelly]

A long time ago I tig welded some damage like that then dressed it with a file and lapped the rotor on with some fine carburundum.

It worked well and never gave a problem.

Just a thought.

[cnap504]

Soon to be started, cleaned carbs, fuel tank, petcock, lapped rotor to taper and secured with Loctite 638, new battery and cables, oil & filter & plugs.  This one sat it a garage dormant for eight years after the alternator rotor spun.

Edited June 16, 2021 by cnap504

[cnap504]

Test ride today after a half dozen garage start ups.  

[Andries]

It's because for some reason Suzuki never had a key slot I used to spot weld the nut once torque up to the crank pin 180° apart and then spot weld the alternator to the nut 180° apart never had a problem again.

[cnap504]

On 6/21/2021 at 6:11 PM, cnap504 said:

Test ride today after a half dozen garage start ups.  

New pipe

[Swiss Toni]

Really nice. Good job!